JP2013213585A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing device having further improved reliability by supplying a required amount of lubricating oil.SOLUTION: A lubricating unit 22 supplies to a rolling bearing 16 lubricating oil the amount of which depends on a temperature detected by a temperature detecting sensor TS. With direct and accurate measurement of a temperature inside the rolling bearing 16, a moderate amount of lubricating oil is, therefore, properly supplied to the rolling bearing 16. Thus, a bearing device can be provided which can secure a sufficiently long life even under the conditions of high-speed rotation.

Description

  The present invention is incorporated in a spindle support portion of a machine tool that slides and rotates at a high speed such as a lathe, drilling machine, boring machine, milling machine, grinding machine, honing machine, super finishing machine, and lapping machine. The present invention relates to a bearing device suitable for use in a machine tool spindle.

  A spindle of a machine tool such as that described above usually incorporates a rolling bearing for supporting the spindle, and is generally used in combination with an angular ball bearing or a cylindrical roller bearing. Here, the machining accuracy and productivity of the machine tool largely depend on the rotation speed of the spindle, and in order to increase the productivity, it is necessary to increase the rotation speed of the spindle. However, when rolling bearings are used under high-speed rotation, the heat generation of the bearings increases remarkably, and the contact surface pressure between the rolling elements and the inner and outer rings increases due to centrifugal force. As a result, the possibility of bearing damage represented by wear and seizure increases. In addition, since heat generation increases due to high-speed rotation, there is a possibility that the machine tool is thermally deformed, which also affects the processing accuracy.

  Roller bearings for spindle support by selecting an appropriate lubrication method under high-speed rotation in order to prevent such a fatal problem from occurring in the bearing and to prevent a reduction in machining accuracy due to thermal deformation of the entire machine tool. It is necessary to suppress the heat generation in the as much as possible. On the other hand, the lubrication of rolling bearings for spindle support of machine tools that rotate at high speeds provides the cooling effect associated with the supply of lubricating oil. (See Patent Document 1).

JP 2003-278773 A

  However, as seen in Patent Document 1, although there is a conventional technique that focuses on the amount of lubricating oil, there is no one that aims at supplying an appropriate amount of lubricating oil by focusing on the actual bearing temperature. . In the conventional technology as described above, it is difficult to directly measure the temperature of a bearing during operation and supply an appropriate amount of lubricating oil.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a bearing device having improved reliability by supplying a necessary amount of lubricating oil.

The bearing device of the present invention is a bearing device having a rolling bearing having an outer ring, an inner ring, and rolling elements disposed between the two rings, a temperature sensor for measuring the temperature inside the rolling bearing, and a lubrication unit. ,
The lubricating unit supplies lubricating oil in an amount corresponding to the temperature detected by the temperature sensor to the rolling bearing.

  According to the present invention, since the lubrication unit supplies the rolling bearing with an amount of lubricating oil corresponding to the temperature detected by the temperature sensor, by directly and accurately measuring the temperature inside the rolling bearing. An appropriate amount of lubricating oil is appropriately supplied to the rolling bearing, thereby providing a bearing device that can ensure a sufficiently long life even under high-speed rotation conditions.

  The temperature sensor is formed by exposing and developing a fine pattern on a resist applied to the surface of a substrate using a mask, and further depositing a metal film on the fine pattern by sputtering and then removing the residual resist. It is preferable. Since such a temperature sensor can be manufactured extremely thin and does not require a large mounting space, it can be mounted in any location within the bearing device, and accurately measures the temperature of the part that is originally desired to be measured. be able to.

  The bearing device is preferably used for a machine tool spindle.

It is an axial sectional view of the rolling device according to the present embodiment. It is a perspective view which expands and shows temperature sensor TS. It is sectional drawing of the spindle apparatus for machine tools incorporating the rolling bearing shown in FIG. FIG. 3 is a diagram illustrating a configuration of a lubrication unit 22. It is a figure which shows the result of having simulated the temperature rise of the rolling bearing when operating the spindle apparatus for machine tools.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an axial sectional view of a rolling bearing used in the present embodiment. The rolling bearing (angular ball bearing) 16 includes an outer ring 16a, an inner ring 16b, a ball 16c as a rolling element disposed between both the wheels 16a and 16b, and a cage 16d that holds the balls 16c at equal intervals in the circumferential direction. Have. The outer ring 16a has a raceway surface 16e on its inner periphery. The inner ring 16b has a raceway surface 16f on the outer periphery thereof. The ball 16c can be made of ceramic such as silicon nitride or silicon carbide.

  A temperature sensor TS is attached to the inner peripheral surface other than the raceway surface 16e of the outer ring 16a with an adhesive. The wiring from the temperature sensor TS is drawn out from the inner peripheral surface of the outer ring 16a to the outside through the end surface. In FIG. 1, the thickness of the temperature sensor TS is exaggerated.

  FIG. 2 is an enlarged perspective view showing the temperature sensor TS. In FIG. 2, the temperature sensor TS has a substrate TSa and a fine resistance pattern TSb formed on the substrate TSa. The resistance pattern TSb is composed of a single platinum line having a narrow line width. The resistance pattern TSb changes in overall length and changes in resistance value when the substrate TSa expands or contracts according to temperature. The temperature can be measured by passing a current through.

  A method for manufacturing the temperature sensor TS will be described. On the surface of a silicon substrate with an oxide film (thickness: 200 μm) as an insulating film, a photoresist of about 2 μm thickness (OFPR800LB manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied by spin coating and pre-coated at 90 ° C. for 8 minutes Processed. Thereafter, exposure was performed using a mask corresponding to the resistance pattern TSb (EMA-400 manufactured by Union Optical Co., Ltd.), and development was performed using a developer (MND3 manufactured by Tokyo Ohka Co., Ltd.). This was finally rinsed with ultrapure water for 60 seconds.

  Thereafter, a platinum film having a thickness of about 250 nm was deposited on the photoresist by a sputtering method, and residual photoresist on the substrate was removed using a lift-off method with acetone. Then, after cutting | disconnecting to the predetermined chip size with the dicing apparatus, wiring was performed to platinum resistance pattern TSb on a chip | tip. The production of the temperature sensor TS is not limited to the above method, but by using a semiconductor microfabrication technique, it is excellent in mass productivity, miniaturization, and sensor responsiveness associated with miniaturization.

  FIG. 3 is a cross-sectional view of the spindle device for machine tools incorporating the rolling bearing shown in FIG. The spindle device 100 is a spindle device for a machine tool that employs a jacket structure that allows cooling oil to flow through an outer housing, and has a bending flexibility of φ1 to φ3.2 mm (here, an outer diameter of φ1.6 mm as an example). The pressure tube 10 made of stainless steel having an inner diameter φ of 1.0 mm is routed in the spindle device 100 and the pressure tube 10 is connected to the nozzle top 12. This pressure-resistant tube 10 made of stainless steel has been subjected to bright annealing treatment and is flexible, so it can be easily bent by hand, and it is a pipe suitable for supplying a small amount of lubricating oil with little pipe expansion due to pressure. .

  The spindle device 100 includes a spindle shaft 14, a plurality of (four in the illustrated example) rolling bearings 16 that rotatably support the spindle shaft, an inner housing 18 that covers the outside of the rolling bearing 16, and the spindle device 100. An outer housing 20 that covers the outer side, and is formed in a communication hole 24 for supplying lubricating oil formed in the outer housing 20 along the axial direction from the lubricating unit 22 that is a supply source of the lubricating oil, or in the inner housing 18. The pressure-resistant tube 10 connects to the nozzle top 12 disposed in the inner housing 18 through the opening 86. That is, the nozzle top 12 is a nozzle that intermittently and directly injects a small amount of lubricating oil to the rolling bearing 16. The pressure tube 10 is a pipe that guides the lubricating oil discharged from the lubricating unit 22 to the nozzle top 12.

  The outer housing 20 includes outer cylinders 28 and 29 that surround the outer periphery of the inner housing 18, and a rear lid 32 that is fixed to the end surface of the outer cylinder 29. The rolling bearings 16 are arranged at a predetermined interval in the axial direction so that the rolling bearings 16 are paired and supported by the front side and the rear side of the spindle shaft 14. The outer ring outer diameter surface is tightly fitted and fixed to the inner peripheral surface of the inner housing 18, the outer ring of the foremost rolling bearing 16 abuts against the outer ring retainer 34 and is non-rotatably locked, and the last rolling bearing 16 The outer ring is locked to the outer cylinder 28 via the outer ring retainer 36 so as not to rotate while being elastically biased in the axial direction by a spring 38. Further, the inner ring inner surface of each rolling bearing 16 is fixed to the outer peripheral surface of the spindle shaft 14 by fitting, and the rolling bearing 16 is axially disposed between the rolling bearings 16 on the front side and the rear side, respectively. A spacer 40 is provided for fixing to the door.

  As shown in the figure, a cooling groove 42 is provided on the outer diameter of the inner housing 18, and cooling oil from a cooling unit (not shown) circulates in the cooling groove to cool the outer housing 20. That is, the spindle device 100 is configured to have a cooling function by an outer cylinder cooling system. Although the spindle shaft 14 in this embodiment is supported horizontally, for example, when used in a machining center, it may be used vertically or inclined.

  Next, the lubrication unit 22 will be described. FIG. 4 is a diagram illustrating the configuration of the lubrication unit 22. As shown in this figure, in the lubrication unit 22, a rod body 46 made of a super-magnetostrictive element having a positive characteristic is fixed to the case 50 via a preload adjusting mechanism 48 at one end 46 a in the axial direction of the rod body 46. . When a magnetic field is applied, the rod 46 extends in the axial direction due to a magnetostriction phenomenon (Joule effect).

  As the preload adjusting mechanism 48, for example, a screw mechanism that protrudes in the axial direction of the rod body 46 by rotation and can press the one end portion 46a of the rod body 46 can be used. The other end 46b in the axial direction of the rod 46 is a pressure transmission member 52 that urges the rod 46 toward the preload adjusting mechanism 48 to transmit pressure without causing a gap (play) in the axial direction of the rod 46. The rod body 46 is connected to the piston 54 through the pressure transmission member 52. The piston 54 is slidably disposed inside the cylinder 56, and the cylinder 56 and the piston 54 form a pump chamber.

  The cylinder 56 is provided with a suction flow path 58 for supplying lubricating oil to the pump chamber, and the lubricating oil is prevented from flowing out from the pump chamber in the middle of the flow path to the suction port 59 of the suction flow path 58. A suction side check valve 60 comprising a check valve is provided. Further, the cylinder 56 is provided with a discharge flow path 62 for discharging the lubricating oil discharged from the pump chamber, and in the middle of the flow path to the discharge port 63 of the discharge flow path 62, the lubricating oil for the pump chamber is provided. A discharge side check valve 64 comprising a check valve for preventing the introduction of the gas is provided.

A coil 66 is coaxially provided on the outer periphery of the rod 46, and a yoke 68 made of a magnetic material that forms a magnetic circuit with the rod 46 is provided outside the coil 66. The drive circuit 70 is electrically connected to the coil 66. The drive circuit 70 receives a signal corresponding to the temperature measured from the temperature sensor TS, and outputs a current for generating a magnetic field accordingly. When this current is applied to the coil 66, the rod body 46 receives and expands the magnetic field generated from the coil 66, so that the lubricating oil in the pump chamber supplied through the suction passage 58 passes through the discharge passage 62. It is discharged from the discharge port 63. The discharged lubricating oil is discharged from the nozzle top 12 through the pressure tube 10. At this time, the discharge amount per shot is as small as 0.5 to 10 mm ^3, and the discharge pressure is 1 MPa or more, and the discharge is intermittently performed.

  The present inventors assembled the rolling bearing 16 in which the temperature sensor TS manufactured by the above method is attached to the raceway surface 16e of the outer ring 16a to the spindle device shown in FIG. 3, and based on the temperature measurement result of the temperature sensor TS. The rolling bearing 16 is supplied when the lubricating oil amount of the lubricating unit 22 is adjusted and supplied (with feedback control) and when the lubricating oil of the lubricating unit 22 is supplied intermittently (without feedback control) regardless of the temperature. The temperature change of was simulated. FIG. 5 shows the simulation result of the temperature change in the state where the atmospheric temperature is 25 ° C., 20,000 rpm, and the rotation time is one hour. When the lubricating oil of the lubricating unit 22 is intermittently supplied, since a certain amount of lubricating oil is supplied every certain time, there is a problem that the bearing temperature is difficult to stabilize. On the other hand, when the temperature information is measured in real time by the temperature sensor TS and the supply timing and supply amount of the lubricating oil is controlled based on the information and supplied from the lubrication unit 22, the bearing temperature is very stable. I understand that.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the temperature sensor TS may be disposed on the raceway surface 16e (location A), the cage 16d (location B), or the inner ring 16b (location C) of the outer ring 16a as indicated by a dotted line. The place to be incorporated is not limited to these, and any place of the rolling bearing 16 can be incorporated. Information from the temperature sensor TS is not limited to wired communication, but can be transmitted wirelessly (IC tag or the like) to the drive circuit 70, and the information can be analyzed to supply an appropriate amount of lubricating oil from the lubrication unit 22.

10 pressure-resistant tube 14 spindle shaft 16 bearing 16a outer ring 16b inner ring 16c ball 16d cage 16e raceway surface 16f raceway surface 18 inner housing 20 outer housing 22 lubrication unit 24 communication hole 25 ambient temperature 28 outer cylinder 29 outer cylinder 32 rear cover 38 spring 40 Spacer 42 Cooling groove 46 Rod 46a Axial end 46b Axial other end 48 Preload adjusting mechanism 50 Case 52 Pressure transmission member 54 Piston 56 Cylinder 58 Suction channel 59 Suction port 60 Suction side check valve 62 Drain channel 63 Discharge port 64 Discharge side check valve 66 Coil 68 Yoke 70 Drive circuit 86 Opening portion TS Temperature sensor TSa Substrate TSb Resistance pattern

The bearing device of the present invention is a bearing device having a rolling bearing having an outer ring, an inner ring, and rolling elements disposed between the two rings, a temperature sensor for measuring the temperature inside the rolling bearing, and a lubrication unit. ,
The lubrication unit is adapted to supply an amount of lubricating oil corresponding to the temperature detected by the temperature sensor to the rolling bearing ,
The temperature sensor consists only of a silicon substrate with an insulating film and a resistance pattern of a platinum thin film formed on the silicon substrate. From a single thin line using a mask on a resist applied on the surface of the substrate. A zigzag fine pattern to be formed is exposed and developed, and a platinum film is deposited on the fine pattern by sputtering, and then the residual resist is removed to form the outer ring as a starting ring .

Claims (3)

In a bearing device having an outer ring, an inner ring, a rolling bearing having a rolling element disposed between the two wheels, a temperature sensor for measuring the temperature inside the rolling bearing, and a lubrication unit,
The lubricating unit supplies the rolling bearing with an amount of lubricating oil corresponding to the temperature detected by the temperature sensor.   The temperature sensor is formed by exposing and developing a fine pattern on a resist applied to the surface of a substrate using a mask, and further depositing a metal film on the fine pattern by sputtering and then removing the residual resist. The bearing device according to claim 1, wherein:   The bearing device according to claim 1, wherein the bearing device is used for a spindle for a machine tool.

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